public final class JapaneseTokenizer extends Tokenizer
This tokenizer sets a number of additional attributes:
BaseFormAttribute
containing base form for inflected
adjectives and verbs.
PartOfSpeechAttribute
containing part-of-speech.
ReadingAttribute
containing reading and pronunciation.
InflectionAttribute
containing additional part-of-speech
information for inflected forms.
This tokenizer uses a rolling Viterbi search to find the
least cost segmentation (path) of the incoming characters.
For tokens that appear to be compound (> length 2 for all
Kanji, or > length 7 for non-Kanji), we see if there is a
2nd best segmentation of that token after applying
penalties to the long tokens. If so, and the Mode is
JapaneseTokenizer.Mode.SEARCH
, we output the alternate segmentation
as well.
Modifier and Type | Class and Description |
---|---|
static class |
JapaneseTokenizer.Mode
Tokenization mode: this determines how the tokenizer handles
compound and unknown words.
|
static class |
JapaneseTokenizer.Type
Token type reflecting the original source of this token
|
AttributeSource.State
Modifier and Type | Field and Description |
---|---|
static JapaneseTokenizer.Mode |
DEFAULT_MODE
Default tokenization mode.
|
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
JapaneseTokenizer(AttributeFactory factory,
UserDictionary userDictionary,
boolean discardPunctuation,
JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer.
|
JapaneseTokenizer(UserDictionary userDictionary,
boolean discardPunctuation,
JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer.
|
Modifier and Type | Method and Description |
---|---|
int |
calcNBestCost(java.lang.String examples) |
void |
close()
Releases resources associated with this stream.
|
void |
end()
This method is called by the consumer after the last token has been
consumed, after
TokenStream.incrementToken() returned false
(using the new TokenStream API). |
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter ) use this method to advance the stream to
the next token. |
void |
reset()
This method is called by a consumer before it begins consumption using
TokenStream.incrementToken() . |
void |
setGraphvizFormatter(GraphvizFormatter dotOut)
Expert: set this to produce graphviz (dot) output of
the Viterbi lattice
|
void |
setNBestCost(int value) |
correctOffset, setReader
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
public static final JapaneseTokenizer.Mode DEFAULT_MODE
JapaneseTokenizer.Mode.SEARCH
.public JapaneseTokenizer(UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
Uses the default AttributeFactory.
userDictionary
- Optional: if non-null, user dictionary.discardPunctuation
- true if punctuation tokens should be dropped from the output.mode
- tokenization mode.public JapaneseTokenizer(AttributeFactory factory, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
factory
- the AttributeFactory to useuserDictionary
- Optional: if non-null, user dictionary.discardPunctuation
- true if punctuation tokens should be dropped from the output.mode
- tokenization mode.public void setGraphvizFormatter(GraphvizFormatter dotOut)
public void close() throws java.io.IOException
Tokenizer
If you override this method, always call super.close()
, otherwise
some internal state will not be correctly reset (e.g., Tokenizer
will
throw IllegalStateException
on reuse).
NOTE:
The default implementation closes the input Reader, so
be sure to call super.close()
when overriding this method.
public void reset() throws java.io.IOException
TokenStream
TokenStream.incrementToken()
.
Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.
If you override this method, always call super.reset()
, otherwise
some internal state will not be correctly reset (e.g., Tokenizer
will
throw IllegalStateException
on further usage).
public void end() throws java.io.IOException
TokenStream
TokenStream.incrementToken()
returned false
(using the new TokenStream
API). Streams implementing the old API
should upgrade to use this feature.
This method can be used to perform any end-of-stream operations, such as setting the final offset of a stream. The final offset of a stream might differ from the offset of the last token eg in case one or more whitespaces followed after the last token, but a WhitespaceTokenizer was used.
Additionally any skipped positions (such as those removed by a stopfilter) can be applied to the position increment, or any adjustment of other attributes where the end-of-stream value may be important.
If you override this method, always call super.end()
.
end
in class TokenStream
java.io.IOException
- If an I/O error occurspublic boolean incrementToken() throws java.io.IOException
TokenStream
IndexWriter
) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpl
s with the attributes of the next
token.
The producer must make no assumptions about the attributes after the method
has been returned: the caller may arbitrarily change it. If the producer
needs to preserve the state for subsequent calls, it can use
AttributeSource.captureState()
to create a copy of the current attribute state.
This method is called for every token of a document, so an efficient
implementation is crucial for good performance. To avoid calls to
AttributeSource.addAttribute(Class)
and AttributeSource.getAttribute(Class)
,
references to all AttributeImpl
s that this stream uses should be
retrieved during instantiation.
To ensure that filters and consumers know which attributes are available,
the attributes must be added during instantiation. Filters and consumers
are not required to check for availability of attributes in
TokenStream.incrementToken()
.
incrementToken
in class TokenStream
java.io.IOException
public int calcNBestCost(java.lang.String examples)
public void setNBestCost(int value)
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